Be able to describe the process by which each of the classes of major nutrient m

Question

Be able to describe the process by which each of the classes of major nutrient macromolecules – carbohydrates, proteins, fats - is digested and how the broken down nutrients from each class are absorbed across the epithelial lining and how they reach the systemic circulation (i.e. via the hepatic portal vein and thence through the liver, or via the lymphatic system, etc). In the case of fats, understand in detail how they are packaged into forms that allow transport on either side of the epithelial membrane, and in the circulation.

Explanation / Answer

digestive process:

ingestion : intake of food into the mouth.

movement: transport of food along digestive tract (contraction of ringed muscles, resulting in peristalsis)

mechanical: process that allow easier passage of food through the tract (physically breaking food into smaller bits so enzymes can chemically break it down)

MASTICATION and PERISTALSIS

chemical digestion: chemical breakdown of food into their building blocks, chemicals come from salivary glands, stomach,pancreas, gall bladder and intestinal lining.

absorption : after digestion, nutreints absorbed across the wall of the small intestine into the blood stream.in it travel through body to be delivered to cells. stomach (alcohol), large intestine ( water,electrolytes)

elimination: movement of waste material (feces) to outside of body via anus. contain indigestible , gut bacteria.

digestion and absorption of carbohydrates: starch or very large, branched ,polysaccharides> enzyme salivary amylase( mouth)> small polysaccharides , disaccharides> enzymes pancreatic amylase( pancreas) > disaccharides> intestinal enzymes (duodenum)> monosaccharides

absorbed: capillaries of villi,transported to liver via hepatic portal vein.

digestion and absorption of fats : unemulsified fat > bile (gallbladder)> emulsified fat> pancreatic lipase (pancreas) > glycerol and fatty acids

absorbed: lacteals of villi, dumped into blood stream at the thoracic duct, near heart transport to live via hepatic artery.

digestion and absorption of proteins : proteins >hcl (stomach) >unravelled proteins> enzyme pepsin (stomach) > smaller polypeptides> enzyme trypsin/ chymotrypsin (pancreas) > dipeptides> intestinAL enzymes > amino acids

absorbed: capillaries of villi, transported to liver via hepatic portal vein.

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